Optimizing double up legumes systems for sustainable intensification in Malawi

Abstract

Smallholder farmers in low and mid altitude agro-ecological zones of southern Africa practice maize-groundnut crop rotations. Due to limited land available for cultivation, farmers practice intercropping of groundnut with pigeonpea in a system known as ‘double up legumes’ to optimize crop productivity. The productivity of double legume intercrops could be influenced by careful selection of varieties that match with amount and distribution of rainfall during the crop season. Knowledge on the productivity of newly released pigeonpea and groundnut varieties grown in intercrops is lacking in the region, given their variability in terms of plant architecture, duration of growth and growth habits. A study was conducted to identify best fit groundnut and pigeonpea varieties for intercropping systems that optimize resource use efficiency and yield and improve economic returns to smallholder farmers. Treatments consisted three varieties each for groundnut and pigeonpea arranged as a factorial structure in a randomized complete block design with three replications. These were assessed at Chitala and Chitedze Research stations, representing low and mid altitude agro-ecological zones respectively for two seasons (2016-2018). In general, intercepted PAR and photosynthetic efficiency were greater for groundnut in intercrops with medium and long duration pigeonpea varieties resulting in more radiation use efficiency than sole crops. Sole crops of groundnut and pigeonpea produced significantly more grain yield than respective intercrops of groundnut and pigeonpea. Among intercrops, in the mid altitude agro-ecological zone of Chitedze, short duration groundnut variety, CG13 in intercrops with medium duration pigeonpea variety, Mwaiwathualimi gave 520 kg ha-1 more grain yield than intercropping CG13 with short duration pigeonpea variety, Chitedze 1. Similarly, at Chitala, groundnut grain yield in intercrops with long duration pigeopea variety, Kachangu was 289 kg ha-1 greater than intercropping groundnut with Chitedze 1. Pigeonpea grain yields were not affected by intercropping with groundnut. However, Chitedze 1 gave 547 and 668 kg ha-1 more pigeonpea grain yield than Kachangu at Chitala and Chitedze respectively. Land equivalent ratios (LERs) of all intercrop combinations were greater than unity indicating more efficient and productive use of environmental resources by intercrops. Economic returns and benefit-cost ratios were greater for intercrops than either sole crop. Intercropping short duration groundnut variety, CG13 with medium to long duration pigeonpea varieties was the most productive and lucrative system. This suggests that careful selection of varieties in intercrops with different architecture and growth habits are complementary and contribute to the sustainable utilization of limited land resources that enhance resource use efficiency, yield and economic returns.